—Second, the FDA may approve the drug but slap on a severe Black Box warning on the prescribing information that tells doctors about a risk that patients might get thyroid cancer. A similar warning is on the label for Novo Nordisk’s liraglutide (Victoza). If this happens, Kasimov says the stocks will still go up, but investors may fret about whether large numbers of primary care doctors will be willing to prescribe it. He estimates there’s about a one in four chance this will happen.

—Third, and the most likely, the FDA delays the exenatide once-weekly application. This will come in what the agency calls a “complete response” letter, but it only asks for “minor” data from clinical trials that have already been completed. As long as the agency’s request is minor, such as asking for some additional data from a study known as Duration-5, then the companies can probably re-submit their application again by the end of June, and still win clearance for the U.S. market by the end of 2010. There’s a 50 percent chance this will happen, Kasimov says.

—Fourth, the FDA could issue a painful “complete response” letter that says the drug needs additional data from an ongoing clinical trial, or that it will need to wait for long-term follow up to prove that exenatide has a beneficial effect on cardiovascular health of diabetes patients. Amylin stock would probably dive 50 percent on this kind of nastygram, and Alkermes would drop 33 percent, Kasimov says. There’s maybe a 10 percent chance of that happening.

Pops wasn’t about to get into this sort of handicapping about what the FDA may or may not do on the eve of decision day for this product. But he did remind me of a state-by-state graphic produced by the Centers for Disease Control and Prevention which I’ve seen before but is still shocking every time I see it. It visually depicts how obesity rates have shot up since 1985.

It would obviously be better if people exercised more, ate less, and came down with fewer cases of diabetes. But barring that, the country is cruising toward staggering health bills for all the heart attacks, strokes, blindness, and limb amputations that stem from chronic diabetes. The drugmakers’ argument is a pretty familiar one—spend a couple billion on our drug, and save a few billion more over time on all the downstream effects of untreated diabetes.

“It’s an amazingly big problem,” Pops says. To borrow a phrase from some lawmakers who talk about “bending the curve” as a reference to curbing the ever-increasing U.S. healthcare bill, Pops says, “if more people keep getting Type 2 diabetes, you can’t bend the curve.”